Base for radiotubes



Oct. 15, 1929. c. J. TERRILL 1,731,832

BASE FOR RADIOTUBES Filed Nov. 8, 1926 till rates CLAIR J'. TERRILL, OF DAYTON, OHIQ, ASSIGNOE TO THE K'URZ-KASGH CQMPANY,

DAYTON, OHIO, A CORPQH-ATIOTM 0F ()HIU BASE FOR RADTOTUBES Application filed November 3, 1926.

My invention relates to thermionic valves or radio tubes and the like and more particularly to an improved base therefor adapted to minimize the transferance of energy be tween the various circuit leads and contact prongs.

The standard and conventional radio tube construction at the present time includes either an evacuated or a gas filled vessel or bulb usually of glass, containing the various elements i. e., the cathode or filament. the grid or modulating element, and the plate or anode element. It is customary to provide a cup shaped base of insulating material into which the vessel is seated and through which circuit leads extend from the elements to corresponding contact lingers or prongs projecting from the bottom of the base. Although such contact lingers or prongs are spaced apart and separated by intermediate areas of insulating material there occurs never-the-less an intertranster of electrical energy, particularly at high radio frequencies, and current losses and leakage from one terminal prong to another either through the material of the base or over the surface there of due to hygroscopic effects.

In the present invention there is contemplated the separation of the contact terminals or prongs by an intervening air gap, which altords a most ellicient dielectric resistance.

To this end a radio tube base oi insulating material and of substantially standard design is transversely slotted across its bottom, and intermediate the contact terminals or prongs, thereby lj'orming isolated lugs or cars, each carrying a contact termnial or prong and separated from each other by an intervening air gap.

The object of the invention is to increase the efficiency of thermionic valves and the like by improving the dielectric resistance between the circuit leads and terminals minimizing current losses and t "ansi er of enregy and the elimination of objectionable feed back effects at this point.

With the above primary and other incidental objects in view as will more fully appear in the specification, the invention consists of the features of construction, the parts Serial No. 146,94.

and combinations thereof, and the mode of operation, or their equivalents, as herein after described and set forth in the claims.

in the accompanying drawing, wherein is shown the preferred but obviously not necessarily the only form of embodiment of a the invention Fig. 1 is a perspective view of a thremionic valve or radio tube provided with a base em bodying. the present invention. Fig. 2 is a bottom plan viewthereot. Fig. 3 is a vertical sectional view. Figs. l and 5 illustrate modifications oi": the construction. Fig. dis a bottom plan view of the tube base illustrating a modification wherein the base is recessed intermediate the contact prongs but not perforated. Fig. 7 is a per-- spective view illustrating a modification wherein the slotted openings in the bottom of the base are extended upwardly in the side wall thereof.

Like parts are indicated by similar characters of reference throughout the several views.

In the drawings there is shown a conventional type of radio tube wherein 1 indicates the bulb containing the several elements, and 2 the base of dielectric material in which the bulb 1 is secured and from which project the contact terminals or prongs 3. Two of the prongs or terminal contacts 3 pertain to the cathode or filament, while one of the remaining prongs 3 pertains to the grid element and the other to the plateor anode element.

Transverse slots 4 are formed in the bottom of the base 2 intermediate the prongs 3, thereby leaving separated lugs or ears 5 upon which the prongs 3 are supported. These lugs or cars 5 may be variously shaped and proportioned to increase the intervening air gap and so increase the dielectric resistance. The slots 4 or air gaps may be extended up the sides of the base 2 as shown at 6 to further isolate the lugs 5 and their supported prongs 3.

The air gap base forming the subject here of, is in eilfect a sleeve like body 2 of insulating material having at one end thereof a series of radially disposed internal lugs 5 supporting the contacts 3. The main body or filament terminals.

sleeve 2 is merely a rim exteriorly connecting the lugs 5 and engaging the bulb l. I While the separation of all the contact terminals is preferred, the losses are most likely to occur between the grid and plate or between grid and filament or plate and filament terminalsand are negligible between the two Hence the filament terminals may be carried upon a common sector lug;-.7as shown'inFig. 4 and the. grid and plate terminals may be separatedtherefromiand from each other by intervening air gaps. Likewise if desired only one of the terminals may be solated from theremainmg contact r prongs 3 by providing only an arcuate slot 8 separating thellug or.ear carry ngthe s ngle prongfrom. thesection: of thebottom which 1s common; ,to. the. remaining contact prongs.

The separation, of the circuit lead contacts by an, air gap. is found to. materially! increase theefliciency of thetubes and eliminates much distortion, and current losses and interference due to: radio frequencyactivity between the various, circuits.

As a further modification there is shown in Fig.,,6 air gaps 4 separatinghtherprong sup portingportions5 and which do not extend entirely through. .the material .but comprise depressions in. one or. .both sides of the bottom secti on,,of thebasegl Inalieu ofan open slot extending through the-bottom section suchslots orairgapsjt are,extended onlywpartiall througlitlae material forming grooves: or arupt recesses. Notaonlymay the. prong supporting areas 5" be separated from each.

other bythe grooved ai-r gapsl, but they be. separated. from the. main sleeve. or body 2 bya similar annular depressionn9 Suchannnlar air gap/l may beadvantageous ly' combined with. the openslot construction. as sho\vn-:1n. l*,1g .2., Such grooved depressions interrupt therhygroscopic conductivity over the surface of the-material. and necessitate successive I changes of direction.,--of ;such current leakage which does not readily change 3 its course. Thus theresistance isincreased and such .losses minimized Whiletmaintaini-z ingaclosedbase to excludeair and. moisture fromtheelement leads.

From the above description it will 'beapparent that there is thus provided aconstructionfo'f the character described possessing the.

particular features of advantage before enumerated as desirable but Which obviously is susceptible" of modification, in its form, proportions, and arrangement of parts, with.

out'departing from the principle involved or Havin thus describedmy invention,- I

claim;

1.. A thermionic valve" includingga basese'cured thereto, aiplunal i'tyiof contact termi nals on said-gbaseototbez conneotediby circuit 1 Q filmue aelementsytsaid contact :ter- 9. nnualsbeing; {separated by;=;horizonta1-ly;and;-:

rating by air gaps the portions of the base carrying the individual terminals said slots beingextended=vertieally from the bottomup-Wardly Within theside walls of the base.

3. A base for a radio tube comprising a cup shaped body of dielectric material, and a series of spaced electrical terminals located in the bottom thereof, the bottom being recessed" intermediate the terminals to incr 31150 the dielectric resistance, said recess being extended above the bottom of the body into the.

side Walls of the cup shaped body.

In testimony whereof, I'havehereunto set my hand this 19th day of October, A. D., 1926.

CLAIR J. TERRILL. 

